1. Field of the Invention
The present invention relates to a method of manufacturing a solid-state image sensor.
2. Description of the Related Art
A CMOS solid-state image sensor, which is one type of solid-state image sensor, has a plurality of MOS transistors, such as reset transistors, amplification transistors, transfer transistors, and the like, for processing charges accumulated in photoelectric conversion elements. The threshold voltage of these MOS transistors is controlled by implanting donor ions or acceptor ions into a channel region. In Japanese Patent Laid-Open 11-196331, in order to make the threshold voltages different for each MOS transistor, a step of forming a resist pattern in which openings for channel regions for the intended MOS transistor are formed and a step of implanting ions from the openings to the channel regions are performed for each MOS transistor.